Air compressor check valve. 3/8" Comp x 1/2" MPT with 1/8" FPT side port.  The check valve is a one-way valve that prevents air from back-feeding from the air tank. If your unit has a hard time restarting when trying to cycle or your pressure switch...

Order this if ordering valve plate or a new head.

Old Part Numbers: Z-D26611If your valve is leaking on the side of the switch, do not order this part. Order check valve instead.

Old Part Numbers: D20763, D27254, D206434-Port OEM regulator. The Regulator controls the amount of air to your hose. Replace this if you're not able to adjust the PSI to your hose or if it leaks.   

Old Part Numbers: AC-0558

Old Part Numbers: D24888, D30198, 5135135-00